Conventional devices which are intended for the same use and same purpose as the device of the present invention will be described below. One method is to cut off considerable portions from opposite sides of a washer in order to pass it into a relatively smaller hole. In this case, the washer has to be elliptical, and can be made thick, but can not be made large.
Another method is to use a blind rivet to form a knot at the other side of the hole. This is accomplished by forming creases at the tip of an aluminum tube, and therefore its strength is very low, resulting in that it can not withstand against heavy loads, and its applicability is very limited.
There is a prior invention by the present applicant, which is intended to overcome the above-described disadvantages (the application of the said invention was filed under Korean Patent Application No. 86-6646). The device of this prior invention consists of two or more divided washer sections, through which a guide wire is connected. In this device, each section of the divided washer is passed through the fastening hole to the opposite side of the panel, and then, the two strands of the guide wire are pulled forward in order to make the divided washer sections get together at the head of the bolt. Therefore, this device can not perform the function of a nut, but only the original function of a washer. Further, the fastening strength of this washer is very weak, and therefore, it is liable to fall out from the head of a bolt. In order to prevent such phenomenon, an annular groove is formed on the head of the bolt, while an annular projection is formed on the washer. Further, in order to assure the sure assembling of the washer sections, a plurality of guide holes for the guide wire are required. Such complicated features of the said device pose as the main disadvantage because the manufacturing cost of the device is increased thereby.